The present invention relates to a dental implant, and more particularly to a dental implant having a dual-textured exterior surface.
Dental implants are embedded in the jaw bone and serve to anchor one or more artificial teeth or dentures. Important to the success of such devices is the rigid anchoring of the implant in the bone, and several journal articles and patents have proposed various methods for achieving rigid anchoring (see U.S. Pat. No. 5,344,457, incorporated herein by reference). For example, U.S. Pat. No. 4,713,003, issued to Symington et al. describes an implant that has a tapered external body, resulting in a better distribution of the stresses acting on the device in situ than was achieved with cylindrical body implants. U.S. Pat. No. 5,344,457, issued to Pilliar et al, describes an implant that has a body with a non-porous surface on the upper portion of the implant and a porous surface on the lower portion of the implant. The porous surface provides interstices into which bone is permitted to grow once the implant is accommodated within the bone. As reported in U.S. Pat. No. 5,603,338, issued to Beaty, and incorporated herein by reference, roughening the surface of the implant can also aid in anchoring the implant because osteoblast-like cells attach more readily to the roughened surface than to a smooth surface.
While roughening the surface can improve the anchoring of the dental implant, the roughened surface also tends to attract and to retain bacteria which can result in infection of the tissue surrounding the implant site, particularly after the bone has receded slightly from the top edge of the implant as is commonly noted by dentists practicing implantology. Theoretically, this problem can be minimized by having an implant with a smooth or a non-porous upper portion, as described in the ""457 patent. However in practice, when the implant of the ""457 patent is embedded in the jaw bone, the bone tends to recede along the entire area adjacent to the non-porous upper portion allowing bacteria to accumulate at the interface of the non-porous upper portion and the porous lower portion of the implant. The interstices of the porous portion that permitted bone to connect the implant to the bone now also permit bacteria to burrow into the implant site causing deep-rooted infection and frequently the need for a second surgical procedure.
Thus, it would be beneficial to have a dental implant that includes a porous or beaded lower portion for strong anchoring to the bone and a non-porous portion that prevents bacterial accumulation, the non-porous portion being designed such that bacteria does not easily reach the porous or beaded portion of the implant.
The present invention relates to a dental implant having a smooth-surfaced head, a tapered beaded-surfaced body, and a threaded transition region between the head and body. The beaded or porous surface of the body provides interstices into which bone is permitted to grow once the implant is accommodated within the jaw bone. The head has a wrench-engaging projection, and a smooth exterior surface so that bone anchoring and bacterial accumulation will be deterred. Between the head and the body is a threaded transition region that serves to anchor the implant to the jaw bone, and to provide a barrier between the smooth surface of the head and the beaded surface of the body thereby reducing the bacterial accumulation adjacent to the beaded surface.